Laser-guided construction equipment

ABSTRACT

A construction apparatus ( 12 ) and method of controlling a construction apparatus from a laser source ( 38 ) made up of a substantially non-rotating beam ( 56 ). The construction apparatus includes a body ( 14 ), a construction tool ( 16 ) adapted to move material, a support moveably supporting the construction tool from the body and a control for guiding movement of the construction tool. A control is provided including a camera ( 28 ) that is adapted to capture an illuminated image that is derived from the laser source. The control determines direction information of the illuminated image with respect to the apparatus at least in part from an output of the camera. The control is further adapted to determine separation information of the spot with respect to the body and a physical relationship between the construction tool and the illuminated image. The construction tool ( 16 ) can be guided with respect to the illuminated image as a function of the direction and separation information and the physical relationship between the construction tool and the illuminated image.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. provisional patentapplication Ser. No. 60/202,256, filed on May 5, 2000, the disclosure ofwhich is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] It has been known to utilize a laser generator in associationwith a construction implement in order to assist in the control of theimplement. Such known systems utilize a separate laser generator whichgenerates a laser plane in order to provide a reference, sethorizontally or at a grade, in order to assist, either manually orautomatically, excavating to a given depth. Such laser planes may begenerated either by sweeping a beam in a plane or by utilizing an opticto convert a beam to a plane. While useful, such known systems requireextensive setup and are limited in application. Such known systems alsouse inclination sensors, rotary angle monitors, and the like, to monitorposition and orientation of the various members making up thearticulated support. Such devices are exposed to the elements at theirpositions of usage on the articulated support and typically require thatwiring be strung along the moveable articulated support.

SUMMARY OF THE INVENTION

[0003] The present invention provides a construction apparatus whichutilizes laser guidance in a new and unique fashion to enhance thefunctionality of a construction implement. This is accomplished byutilizing an imaging sensor, or camera, to capture an image derived froma laser source. The laser source is a beam that is substantiallynon-rotating. This allows the present invention to perform functionsbeyond those of the prior excavator controls, as well as to provide aself-contained apparatus that does not require set-up and take-down of aseparate laser generator. Also, the present invention provides thecapability for establishing, not only the depth, but also the geographicposition of the construction tool, thereby further enhancing thefunctionality of the construction apparatus.

[0004] A construction apparatus and method of controlling theconstruction apparatus from a laser source made up of a substantiallynon-rotating beam, according to an aspect of the invention, includesproviding a body having a cab that is adapted to be moveably supportedby a surface. A construction tool is provided that is adapted to movematerial. A support moveably supports the construction tool from thebody. A control is provided for guiding movement for the constructiontool. The control includes a camera that captures an illuminated imagederived from a laser source. The control determines directioninformation of the illuminated image at least in part from an output ofthe camera. The control further determines location information of theconstruction tool. In this manner, the construction tool can be guidedwith respect to the illuminated image derived from the laser source as afunction of the direction information and location information.

[0005] These and other objects, advantages and features of thisinvention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006]FIG. 1 is a side elevation of a construction apparatus, accordingto the invention;

[0007]FIG. 2a is a top plan view of a laser source useful with theconstruction apparatus in FIG. 1;

[0008]FIG. 2b is a side elevation of the laser source in FIG. 2a;

[0009]FIG. 3a is a perspective view of an imaging sensor, or camera,that is useful with the invention;

[0010]FIG. 3b is the same view as FIG. 3a of an alternative embodimentthereof;

[0011]FIG. 3c is a top plan view of an imaging sensor array, accordingto the invention;

[0012]FIG. 4 is a block diagram of an electronic control system,according to the invention;

[0013]FIG. 5a is the same view as FIG. 1 of an alternative embodiment ofthe invention;

[0014]FIG. 5b is a front elevation of the construction apparatus in FIG.5a as viewed from direction 5 b-5 b.

[0015]FIG. 6 is the same view as FIG. 1 of another alternativeembodiment of the invention;

[0016]FIG. 7 is the same view as FIG. 1 of another alternativeembodiment of the invention;

[0017]FIG. 8 is the same view as FIG. 1 of yet another alternativeembodiment of the invention; and

[0018]FIG. 9 is an elevation of an operator display panel as viewed byan operator.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Referring now specifically to the drawings, and the illustrativeembodiments depicted therein, a construction apparatus 10, which isillustrated as an excavator 12, includes a body 14, a construction toolin the form of a bucket 16 and a support 18 for moveable supportingbuckets 16 from body 14 (FIG. 1). Body 14 includes an operator cab 20and is moveably supported on a surface by propelling devices 22, such aswheels, treads, caterpillars, or the like.

[0020] Construction apparatus 10 further includes amicrocontroller-based control 24 including a microcomputer 26 and animaging sensor, or camera, 28 having an output 30 in order to supplycaptured image data to microcomputer 26 (FIG. 4). Control 24additionally includes an operator display 32, positioned in cab 20 inorder to display to the operator information pertaining to the locationof bucket 26, as will be set forth in more detail below. With suchinformation displayed to the operator with display 32, the operator canmanually actuate convention controls (not shown) in order to manipulatebucket 16 while viewing display 32. Optionally, control 24 may includean actuator system 34 to operate hydraulic valves (not shown) in orderto control the movement of support 18 such that operation of bucket 16is under full automatic control of the control 24 unless overridden bythe operator. Control 24 may additionally include a GeographicPositioning System, or Global Positioning System, (GPS) 36 whichreceives signals from geostationary satellites (not shown) in order toprovide an indication of the geographic position of body 14 in threedimensions including elevation, latitude and longitude. Such geographicpositioning systems are commercially available and well-known in theart.

[0021] Construction apparatus 10 further includes a laser source 38 inthe form of a non-rotating laser beam which is directed toward surface Sthereby producing an illuminated image that is derived from laser source38, as will be explained in more detail below. Camera 28 has a field ofview extending generally from f₁ to f₂, both vertically and laterally,thereby capturing images within the field of view f₁, f₂.Advantageously, camera 28 is positioned on body 14 under articulatedsupport 18. This provides a good view of the work site as well asprovides protection for camera 28 from debris, and the like, that mayotherwise fall on the sensor. The camera may further be protected byshutters, cleaners, heaters, and the like, as are known in the art. Theilluminated image I derived from laser source 38 is captured by imagingsensor 28 along direction D_(I).

[0022] Camera 28 includes a pixilated image plane 40 including an arrayof pixels 42 for sensing light levels of an image captured by imagingsensor 28 (FIGS. 3a-3 c). Imaging sensor 28 further includes a focusingoptic 44 in order to focus images onto image plane 40. Preferably,focusing optic 44 is a wide-angle lens in order to provide a wide fieldof view f₁, f₂. Imaging sensor 28 may determine the direction D_(I) bydetermining which pixel or pixels 42 intercept image I as illustrated inFIG. 3a. As will be understood by a skilled artisan, the pixel or pixels42 that are intercepted by image I are related to the direction D_(I)with respect to imaging sensor 28.

[0023] Alternatively, imaging sensor 28 may be mounted on one or moreservo-driven gimbals 46 which are capable of repositioning image plane40 under the feedback control of microcomputer 26 in order to trackimage I by adjusting servos S₁, S₂ until image I is centered amongpixels 42 (FIG. 3b). Computer 26 is able to determine direction D_(I)from the positioning information from servos 46 as would be understoodby the skilled artisan. Imaging sensor 28, 28′ may be a single sensor ormay be arranged in a sensor array 28″, illustrated in FIG. 3c, includingmultiple imaging sensors arranged side-by-side in order to increase thefield of view F₁, F₂. Cameras 28, 28′, 28″ are either CCD imagingsensors or MOS sensors, both of which are of low cost and commerciallyavailable in combination with focusing optic 44 from various sources.

[0024] Microcomputer 26 may be programmed with image discriminationsoftware, such as shape recognition software 48. Such software is knownin the field of inspection systems for determining whether manufacturedcomponents meet design requirements. Shape recognition software 48allows microcomputer 26 to capture images of one or more features ofbucket 16 and support 10. This may include teeth 50 of bucket 16. Aswould be apparent to the skilled artisan, microcomputer 26 is capable ofusing shape recognition software 48 to determine at least generallocation information of teeth 50 from images captured by imaging sensor28, particularly the relationship between teeth 50 and illuminated imageI. With location information of the bucket teeth 50 known with respectto illuminated image I, either the operator viewing display 32 or thecontrol operating actuator 34 can position teeth 50 in relationship tothe illuminated image I derived from laser source 38.

[0025] In the illustrative embodiment, laser source 38 generates animage I having a pattern that varies as a function of separation betweenlaser source 38 and illuminated image I. Referring to FIG. 2a, this maybe accomplished by providing two or more lasers 54 a, 54 b generatingbeams 56 a, 56 b that are distinguishable from each other. This may beaccomplished by utilizing polarization, modulation, phasing, color orother means to allow beams 56 a, 56 b to be distinguishable from eachother by camera 28. Lasers 54 a, 54 b may generate beams in the red,infrared, green, blue, or other portions of the spectrum. Camera 28 isadapted to distinguish beams 56 a, 56 b such as by having correspondingpolarity sensors, color sensors, demodulation means, or the like. As canbe seen by reference to FIG. 2a, beams 56 a, 56 b intersect. To the leftof the intersection, as viewed in FIG. 2a, beam 56 b is above beam 56 a.As viewed in FIG. 2a, to the right of the point of intersection, beam 56a is above beam 56 b. At the point of intersection of the beams 56 a and56 b, a single illuminated image I will be generated and captured byimaging sensor 28.

[0026] If beams 56 a, 56 b contact ground S closer to body 14 than wherethey intersect, the image produced by beam 56 a will be above the spotproduced by beam 56 b, as viewed in FIG. 2a, or to the right of the spotproduced by beam 56 b as viewed from body 14. In a similar fashion, ifbeams 56 a, 56 b contact surface S further away from body 14 than theirpoint of intersection, the spot produced by beam 56 b will be to theright of the beam produced by 56 a as viewed from body 14. Thisrelationship, as well as the separation between spots produced by thebeams, distinguish the distance of the spots from body 14 allowingcontrol 24 to determine the depth of image I with respect to body 14 byknowing the angle of separation β between the beams and the angle ofinclination of the beams. Moreover, actuators 70 and 72 may be providedto adjust, respectively, the separation angle β and the elevation anglea under control of microcomputer 26 so that control 24 can set a desireddepth. By making adjustments to the angle β between laser generators 54a, 54 b, and the angle of inclination, the image I can be set to producea single spot at a desired depth of dig of teeth 50. This can beaccomplished by microcomputer 26 using suitable algorithms. Moreover,because the spot pattern is different, i.e., the distinguishable spotsfrom beams 56 a, 56 b reverse, if the surface contacted by the beams isabove or below the desired depth, suitable control can be effected toseek desired depth. A dual-axis inclination sensor on body 14 ofexcavator 12 provides a signal to microcomputer 26 to allow anyinclination of body 14 to be factored into the determination of spotdepth. In this manner, excavator 12 can excavate to a desired deptheither manually or automatically. It should be understood that theside-by-side arrangement of beams 56 a, 56 b is for illustrationpurposes only. The beams could, alternatively, be arranged in a verticalplane or any other desired orientation.

[0027] Control 24 may further have the ability to determine positioncoordinates for teeth 50 with respect to body 14 thereby allowingcontrol 24 to determine a geographic position of bucket teeth 50 bycombining offset of the teeth from the body with geographic informationdetermined by GPS receiver 36. GPS receiver 36 may be a direct receiveror a differential receiver of the type known in the art. This allowsexcavator 12 to excavate according to a site plan including complexcontours, such as along an embankment, and the like. Determiningposition coordinates of teeth 50 with respect to body 14 may beaccomplished by using conventional techniques to measure orientation ofthe members making up moveable support 18. These may include, by way ofexample, positioning angle encoders at each pivot 52, inclinationencoders at the members making up support 18, or, otherwise, measuringangles or inclination of the members making up articulated support 18such as disclosed in commonly assigned U.S. Pat. Nos. 4,805,086;4,829,418; 4,884,939; 4,866,641; 4,945,221; 5,742,069; 5,572,809; and5,953,838, the disclosures of which are hereby collectively incorporatedherein by reference. Other techniques may be utilized by control 24 todetermine a coordinate of teeth 50. Software 48 may be able to determinea distance of teeth 50 by comparing a size of the image of teeth 50captured against a database, or the like, in order to match the size ofthe image of the teeth with a distance of teeth from body 14. With suchscheme, it may be desirable to provide a rotary encoder for monitoringvertical axis rotation of body 14 about propelling devices 22.

[0028] In another embodiment, an excavator 12′ includes an imagingsensor 28 which receives an illuminated image I′ produced by a pipelaser 58 and determines a direction D_(I) to image I′ and a distance ofthe image from body 14. In particular, pipe laser 58 produces a laserbeam 60 which impinges a target 62 as disclosed in commonly assignedU.S. Pat. No. 5,621,531, the disclosure of which is hereby incorporatedherein by reference. Distance of image I′ from body 14 may be determinedusing two laterally spaced cameras 28 (FIG. 5b). Using knownrelationships, distance between image I′ and body 14 may be derived fromthe directions of the images captured by both cameras. Distance of imageI′ above the bottom of the trench is a known parameter. As in theprevious embodiment, imaging sensor 28 captures images of image I′ andbucket 16 including teeth 50 to determine information or the location ofilluminated image I′ and the relative orientation of teeth 50 to imageI′. In this manner, control 24 is able to guide teeth 50 with respect toimage I′. This allows the excavator operator or control 24 to guideteeth 50 in a manner to extend the trenches in which pipe P is beinglaid. It may be necessary to restrict movement of support 18, so thatthe bucket is lifted out of the trench before it interferes with theview of image I′ by cameras 28. Alternatively, the control may beconfigured to accommodate momentary disruption of the view. Target 62may include diffractive elements as disclosed in commonly assignedapplication Ser. No. 09/527,372 filed Mar. 16, 2000, the disclosure ofwhich is hereby incorporated herein by reference. This facilitates apipe laser using a beam that operates in the green portion of thespectrum, but could also utilize a beam in the blue, red, or infraredportion of the spectrum.

[0029] Alternatively, excavator 12′ may have a laser unit 38 (not shownin FIG. 5) that generate a non-rotating beam that can be pointed at endsE₁, E₂ of pipe P. With some knowledge of the position of ends E₁, E₂ aswell as the grade of pipe P, the invention comprehends the use of suchinformation to continue the trench in which pipe P is positioned at adesired depth for proper depth and grade of the pipe. One difficultythat may occur is that the starting end E₁ is often backfilled longbefore the entire pipeline is complete. This may be overcome byproviding a mark above ground of the location of E₁ such as by thelocation of a manhole, stake, or the like.

[0030] An operator display panel 32 that is useful with the invention isillustrated in FIG. 9. Operator display panel 32 may include a touchsensitive display panel 78 having one or more hard or soft switches 80that are useful by the operator in controlling the functions of operatordisplay 32. The panel additionally includes a display portion 82 havingan icon 86 illustrating a position of bucket 16 with respect to a gradeline 84 which, as previously set forth, is determined from theilluminated image I captured by camera 28. When the difference inelevation between bucket 16 and grade line 84 is relatively great, gradeline 84 would be off the screen at the bottom. As the differencenarrows, the desired grade line 84 would rise as illustrated. Whenbucket teeth 50 reach grade line 84, the icon 86 would illustrate thesame. Additionally, a distance to grade readout 88 may be provided toillustrate the distance between the bucket teeth and the grade line. Areach line 90 may also be provided in order to illustrate to theoperator the relative position of bucket 16 in a vertical plane.

[0031] The present invention may also be directed to a constructionapparatus in the form of a trencher 112 having a trencher body 114moveably supported by wheels 122 and a construction tool in the form ofa trenching implement 116 which is moveably supported by support 118(FIG. 6). A control system for trencher 112 includes an imaging sensorin the form of a camera 28 and a laser source 38 which produces anon-rotating laser beam which is directed generally in the area of thetrenches being formed by trencher 112. Laser source 38 creates anilluminated beam I in the trench. Camera 28 captures the illuminatedimage I as well as a portion of trenching implement 116 in order toallow the trenching implement to be controlled either manually by anoperator or automatically utilizing principles previously described aswould be understood by the skilled artisan. Trencher body 114 andimplement 116 are as generally described in commonly assigned U.S. Pat.No. 5,559,725, the disclosure of which is hereby incorporated herein byreference.

[0032] The principles of the invention may also be applied to a grader212 having a grader body 214 that is propelled by propelling wheels 222and a construction tool in the form of a blade 216 which is connectedwith body 214 by a support 218 (FIG. 7). A laser source 38 generates anon-rotating laser beam to create an image I at a string S, a road bed,a curb, or the like. An imaging sensor in the form of a camera 28 whichcaptures image I illuminated by laser source 38 and a portion of blade216 in order to control blade 216 utilizing the principles previouslydisclosed herein. Grader 212 is, otherwise, as disclosed in commonlyassigned U.S. Pat. Nos. 5,327,345 and 6,152,238, the disclosures ofwhich are hereby incorporated herein by reference.

[0033] The principles of the invention may also be applied to aconstruction apparatus in the form of a paver 312 having a body 314, ascreed 316, a laser scanner 38, which generates a non-rotating laserbeam that is directed at the previously laid surface thereby generatingan illuminated image I. Illuminated image I is captured by a camera 28along with a portion of screed 316 to allow elevation of screed 316 tobe controlled to a desired pavement elevation (FIG. 8). Paver 312 may bea concrete paver wherein screed 338 would be a concrete screed of thetype that is known in the art. Alternatively, paver 312 may be anasphalt paver for which screed 338 would be an asphalt screed of thetype that is well known in the art.

[0034] Thus, it is seen that the present invention utilizes lasertechnology in a manner previously unknown in the art of constructionmachine control. Such known systems utilize a laser to control the depthof material to be worked as an offset from a stationary laser generator,the present invention provides enhanced flexibility and control of thevarious material working operations. Furthermore, this is accomplishedwith laser generators that are either mounted to the body of theconstruction apparatus or are being utilized for other purposes.Furthermore, the present invention comprehends the use of imagediscrimination software in order to allow the control to monitormovement of the construction tool to thereby guide the construction toolwith respect to the illuminated image formed by the laser generator. Byutilizing a Geographic Positioning System (GPS) mounted to theconstruction apparatus body, actual geographic X, Y coordinates of theconstruction tool may be determined, utilizing an offset between thecoordinates of the construction tool and the construction apparatusbody. This allows the invention to be utilized in earth-formingapplications where complicated contours are laid out for the job site.

[0035] Changes and modifications in the specifically describedembodiments can be carried out without departing from the principles ofthe invention. For example, the controls may be fully digital or atleast partially analog in nature. The invention is intended to belimited only by the scope of the appended claims, as interpretedaccording to the principles of patent law including the doctrine ofequivalents.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A construction apparatus that is adapted to be guided from a laser source made up of a substantially non-rotating beam, said construction apparatus comprising: a body having an operators cab, said body adapted to be moveably supported by a surface, a construction tool adapted to move material, a support moveably supporting said construction tool from said body, and a control for guiding movement of said construction tool; said control comprising a camera that is adapted to capture an illuminated image that is derived from a laser source, said control adapted to determine direction and separation information of the illuminated image with respect to said apparatus, wherein said control determines said direction information at least in part from an output of said camera; said control further adapted to determine a physical relationship of said construction tool with respect to said illuminated image; whereby said construction tool can be guided with respect to the illuminated image as a function of said direction and separation information and said relationship.
 2. The construction apparatus of claim 1 including a display at said cab for displaying information related to said direction and separation information and said relationship.
 3. The construction apparatus of claim 1 wherein said control is adapted to automatically guide said construction tool with respect to said illuminated image by comparing said direction and separation information and said relationship.
 4. The construction apparatus of claim 1 wherein said body comprises an excavator body and said construction tool comprises an excavation bucket.
 5. The construction apparatus of claim 1 wherein said body comprises a grader body and said construction tool comprises a blade.
 6. The construction apparatus of claim 1 wherein said body comprises a trencher body and said construction tool comprises trenching implement.
 7. The construction apparatus of claim 1 wherein said body comprises a paver body and said construction tool comprises a screed.
 8. The construction apparatus of claim 7 wherein said screed comprises one of an asphalt screed and a concrete screed.
 9. The construction apparatus of claim 1 including a laser source comprising a substantially non-rotating beam.
 10. The construction apparatus of claim 9 wherein said control calculates an offset of a portion of said bucket from said body.
 11. The construction apparatus of claim 10 including a geographic positioning system at said body, wherein said control calculates a geographic position of said portion of said bucket by combining said offset with an output of said geographic positioning system.
 12. The construction apparatus of claim 1 wherein said control determines said direction information and said separation information at least in part from said output of said camera.
 13. The construction apparatus of claim 9 wherein said control determines said physical relationship by capturing with said camera a portion of said bucket and said illuminated image.
 14. The construction apparatus of claim 1 wherein said control comprises a microcomputer that is programmed with image discrimination software and wherein said control determines said relationship by recognizing with said software a portion of said construction tool that is captured by said camera.
 15. The construction apparatus of claim 14 wherein said image discrimination software comprises shape recognition software.
 16. A construction apparatus that is adapted to be guided from a laser source made up of a substantially non-rotating beam, said construction apparatus comprising: a body having an operators cab, said body adapted to be moveably supported by a surface, a construction tool adapted to move material, a support moveably supporting said construction tool from said body, and a control for guiding movement of said construction tool; said control comprising a camera that is adapted to capture an illuminated image that is derived from a laser source, said control adapted to determine direction and separation information of the illuminated image with respect to said apparatus, wherein said camera is gimbal mounted and wherein said control determines said direction information by substantially tracking with said camera the illuminated image and by monitoring with said control a position of said camera about said gimbal; said control further adapted to determine a physical relationship of said construction tool with respect to said illuminated image; whereby said construction tool can be guided with respect to the image derived from a laser source as a function of said direction and separation information and said relationship.
 17. The construction apparatus of claim 16 including a laser source comprising a substantially non-rotating beam.
 18. The construction apparatus of claim 17 wherein said laser source is positioned at one end of a pipe and said illuminated image comprises a spot produced by said laser source impinging a target at an opposite end of the pipe.
 19. The construction apparatus of claim 18 including another camera that is gimbal mounted and wherein said control determines said separation information by monitoring positions of said cameras about their respective gimbals.
 20. The construction apparatus of claim 17 wherein said laser source is positioned at said body and directed toward material being moved by said construction tool, thereby creating said illuminated image at said material.
 21. The construction apparatus of claim 20 wherein said control determines said direction information and said separation information at least in part from said output of said camera.
 22. The construction apparatus of claim 16 including a display at said cab for displaying information related to said direction and separation information and said relationship.
 23. The construction apparatus of claim 16 wherein said control is adapted to automatically guide said construction tool with respect to said illuminated image by comparing said direction and separation information and said relationship.
 24. The construction apparatus of claim 16 wherein said control comprises a microcomputer that is programmed with image discrimination software and wherein said control determines an offset of said construction tool from said body by recognizing with said software at least a portion of said construction tool or said support that is captured by said camera.
 25. The construction apparatus of claim 24 wherein said image discrimination software comprises shape recognition software.
 26. A construction apparatus that is adapted to be guided from a laser source made up of a substantially non-rotating beam, said construction apparatus comprising: a body having an operator's cab, said body adapted to be moveably supported by a surface, a construction tool adapted to move material, a support moveably supporting said construction tool from said body, and a control for guiding movement of said construction tool; said control comprising a camera that is adapted to capture an illuminated image that is derived from a laser source, said control adapted to determine direction and separation information of the illuminated image with respect to said apparatus, wherein said camera includes a sensing array and a focusing optic that focuses light onto a portion of said sensing array and wherein said control determines said direction information by determining which portion of said sensing array receives light from said illuminated image; said control further adapted to determine a physical relationship of said construction tool with respect to said illuminated image; whereby said construction tool can be guided with respect to the image derived from a laser source as a function of said direction and separation information and said physical relationship.
 27. The construction apparatus of claim 26 including a laser source comprising a substantially non-rotating beam.
 28. The construction apparatus of claim 27 wherein said laser source is positioned at one end of a pipe and said illuminated image comprises a spot produced by said laser source impinging a target at an opposite end of the pipe.
 29. The construction apparatus of claim 28 including another camera including another sensing array and another focusing optic that focuses light onto a portion of said another sensing array and wherein said control determines said separation information by determining which portions of said sensing arrays receive light from their respective gimbals.
 30. The construction apparatus of claim 27 wherein said laser source is positioned at said body and directed toward material being moved by said construction tool, thereby creating said illuminated image at said material.
 31. The construction apparatus of claim 30 wherein said control determines said direction information and said separation information at least in part from said output of said camera.
 32. The construction apparatus of claim 26 including a display at said cab for displaying information related to said direction and separation information and said relationship.
 33. The construction apparatus of claim 26 wherein said control is adapted to automatically guide said construction tool with respect to said illuminated image by comparing said direction and separation information and said relationship.
 34. The construction apparatus of claim 27 wherein said control comprises a microcomputer that is programmed with image discrimination software and wherein said control determines an offset of said construction tool from said body by recognizing with said software at least a portion of said construction tool or said support that is captured by said camera.
 35. The construction apparatus of claim 34 including a geographic positioning system at said body, wherein said control calculates a geographic position of said construction tool by combining said offset with an output of said geographic positioning system.
 36. A pipe-laying system, comprising: a laser source that is positionable at one end of a pipe and a target that is positionable at an opposite end of the pipe, said laser source generating a beam that produces a spot on said target; an excavator having a body, a bucket and a support moveably supporting said bucket from said body, and a control for guiding movement of said bucket, said body including propelling devices and an operator's cab; said control comprising a camera that is adapted to capture the spot on said target and to determine direction information of the spot on said target with respect to said excavator, wherein said control determines separation information of the spot with respect to the excavator, wherein said control determines said direction information at least in part from an output of said camera; said control further adapted to determine a physical relationship of a portion of said bucket with respect to said illuminated image; whereby said bucket can-be guided with respect to the spot on said target as a function of said direction and separation information and said relationships.
 37. The pipe-laying system of claim 36 including a display at said cab for displaying information related to said direction and separation information and said relationship.
 38. The pipe-laying system of claim 36 wherein said control is adapted to automatically guide said portion of said bucket with respect to the spot on said target by comparing said direction and separation information and said relationship.
 39. The pipe-laying system of claim 36 wherein said camera is positioned below a portion of said body that is joined with said articulated support.
 40. The pipe-laying system of claim 36 including another camera that is adapted to capture the spot on said target and to determine direction information of the spot on said target with respect to said excavator and wherein said control determines said separation information from said direction information of said cameras.
 41. An excavator for excavating material, comprising: a body, a bucket and a support moveably supporting said bucket from said body, and a control for guiding movement of said bucket, said body including propelling devices and an operator's cab; a laser source positioned at said body, said laser source comprising a substantially non-rotating beam that is directable toward material being excavated by said bucket, thereby creating an illuminated image at the material; said control comprising a camera that is adapted to capture the illuminated image and to determine direction information of the illuminated image with respect to the excavator, wherein said control determines separation information of the illuminated image with respect to the excavator, wherein said control determines said direction information at least in part from an output of said camera; said control further adapted to determine a physical relationship of a portion of said bucket with respect to said illuminated image; whereby said portion of said bucket can be guided with respect to the illuminated image at the material as a function of said direction and separation information and said relationship.
 42. The excavator of claim 41 wherein said laser source is adapted to create the illuminated image at the material having a pattern, wherein said pattern varies as a function of separation between said laser source and the illuminated image at the material.
 43. The excavator of claim 42 wherein said control determines vertical depth of the material being moved as a function of said pattern.
 44. The excavator of claim 43 wherein said laser source creates said pattern from at least two laser units generating beams that are distinguishable from each other and at an angle with respect to each other.
 45. The excavator of claim 41 wherein said control comprises a microcomputer that is programmed with image discrimination software and wherein said control determines an offset of said portion of said bucket with said software, said portion of said bucket or said support that is captured by said camera.
 46. The excavator of claim 45 including a geographic positioning system at said body, wherein said control calculates a geographic position of said portion of said bucket by combining said offset with an output of said geographic positioning system.
 47. The excavator of claim 41 including a display at said cab for displaying information related to said direction and separation information and said relationship.
 48. The excavator of claim 41 wherein said control is adapted to automatically guide said portion of said bucket with respect to the material being excavated by comparing said direction and separation information and said relationship.
 49. The excavator of claim 45 wherein said articulated support is made up of multiple members that are articulated with respect to each other and wherein said control determines said offset at least in part by recognizing with said software portions of at least some of said multiple members.
 50. The excavator of claim 49 including a geographic positioning system at said body, wherein said control calculates a geographic position of said construction tool by combining said offset with an output of said geographic positioning system.
 51. The excavator of claim 41 wherein said camera is positioned below a portion of said body that is joined with said articulated support.
 52. A method of controlling a construction apparatus having a body, a construction tool adapted to move material, a support moveably supporting said construction tool from said body, and a control for guiding movement of said construction tool including an operators cab, said body adapted to be moveably supported by a surface, said method comprising: providing a laser source that generates a substantially non-rotating beam and directing said beam with respect to the material to be moved to create an illuminated image with said laser source; providing a camera and capturing with said camera said illuminated image; determining direction information of said illuminated image at least in part from an output of said camera; determining separation information between said illuminated image and said body; determining a physical relationship between said construction tool and said illuminated image; and guiding said construction tool with respect to said illuminated image as a function of said direction and separation information and said relationship.
 53. The method of claim 51 including displaying to an operator information related to said direction and separation information and said relationship and manually guiding said construction tool with the operator.
 54. The method of claim 51 including automatically guiding said construction tool with respect to said illuminated image by comparing said direction and separation information and said relationship.
 55. The method of claim 51 including determining from an output of said camera an offset from the body of a portion of the construction tool.
 56. The method of claim 55 including determining a geographic position of said body and calculating a geographic position of said construction tool by combining said offset with an output of said geographic positioning system.
 57. The method of claim 52 including determining said separation information from an output of said camera. 